Astragalus: Immunity, Telomerase, and Longevity – What the Research Says

Once every few years, a traditional medicinal herb gains a new and brilliant scientific aura, along with a matching price tag. Astragalus (Astragalus membranaceus), known in Chinese medicine as Huang Qi, is a perfect example of this. For thousands of years, its root has been used as a classic "tonic" herb, of the type meant to strengthen vital energy and the body's resistance to disease. So far, a familiar traditional story.

But over the last fifteen years, Astragalus has undergone an image makeover. Researchers discovered that an extract from its root, a molecule called cycloastragenol, can activate the enzyme telomerase, the same enzyme that "lengthens" the ends of chromosomes (telomeres) which shorten with age. From there, the path to marketing Astragalus as an "anti-aging" supplement that lengthens telomeres and slows biological time was short. Very expensive supplements, led by TA-65, were built around this claim. The big question is whether the biology truly supports it, or whether it is mostly clever marketing. In this article, we will separate what Astragalus can actually do from what is promised about it, and explain why we rated it yellow.

What is Astragalus?

Astragalus is a genus of plants in the legume family, and the species used for supplements is primarily Astragalus membranaceus (now also classified as Astragalus mongholicus). Its dried root is a core part of the traditional Chinese medicine toolkit. Here is what is important to understand about it:

• It is a classic "tonic" herb. In Chinese medicine, it is used to support what is called Qi, and is considered an herb that strengthens general resistance, so it is often incorporated into blends for immune support and recovery.
• Its active components are diverse. It contains polysaccharides (long sugar chains), flavonoids, and saponins from the astragaloside group, led by astragaloside IV.
• It is the source of cycloastragenol. Cycloastragenol is a breakdown product (aglycone) of astragaloside IV, and it is the molecule that has received the most attention for its ability to activate telomerase in laboratory studies.
• It has been studied in several contexts. Beyond immunity, its effects on the cardiovascular system, kidney function in some Chinese studies, and as an adjunct to oncological treatments have been examined.

It is important to distinguish between two "identities" of Astragalus on the market. On one hand, there is the regular, relatively inexpensive herbal supplement – root powder or a standard extract – marketed for immune support. On the other hand, there are the targeted and very expensive extracts, led by TA-65, marketed specifically as telomerase activators that "slow aging". The price difference is enormous, and the difference in the strength of evidence is no less significant, as we will see shortly.

The Connection to Immunity and Aging: Two Separate Mechanisms

To understand Astragalus correctly, one must separate two completely different stories that get mixed up in marketing. The first story is immune-inflammatory, and its foundation is relatively good. The second story is about telomerase and aging, and its foundation is much weaker.

First mechanism: Immune regulation and anti-inflammatory effects. The polysaccharides of Astragalus have been studied for their ability to affect immune system cells, including activating macrophages and NK (Natural Killer) cells, and influencing T cells. Concurrently, Astragalus has been linked to regulating key inflammatory pathways, primarily the NF-kB pathway, which may lead to a decrease in the production of pro-inflammatory cytokines like IL-6, TNF-α, and IL-1β. This is a regulatory mechanism, not just "strengthening": the herb is reported to improve markers of cellular immunity on one hand, while curbing inflammation on the other.

Second mechanism: Telomerase activation. This is where cycloastragenol comes in. Telomerase is the enzyme that adds DNA sequences back to the ends of chromosomes, thereby slowing the telomere shortening that occurs with each cell division. In laboratory studies and in isolated cells, cycloastragenol (and to a lesser extent astragaloside IV) has been shown to activate telomerase and lengthen telomeres. From here grew the major hypothesis: if telomeres are lengthened, perhaps cellular aging itself could be slowed. This is an intriguing hypothesis, but it involves a huge logical leap, which we will return to: the fact that a molecule activates an enzyme in cells in a lab dish is very far from proof that it extends healthy lifespan in humans.

Third mechanism: Cardiovascular effects. In some studies, the potential effect of Astragalus and TA-65 on metabolic and cardiovascular markers has been examined, based on its antioxidant and anti-inflammatory properties. Here too, the evidence is more preliminary, but it is part of the overall picture.

Current Evidence

Study 1: Astragalus and the Immune System, Meta-Analysis by Zhang et al. 2023

This is one of the stronger pieces of evidence for an immune effect in humans. In 2023, Zhang et al. published a systematic review and meta-analysis in the journal Complementary Medicine Research that aggregated 19 studies with 1,094 human participants, examining the effect of Astragalus on humoral and cellular immune response.

The findings were consistent: Astragalus intake was associated with a significant increase in CD3 levels and the CD4/CD8 ratio (markers of cellular immunity), alongside a significant decrease in pro-inflammatory cytokines such as IL-6, TNF-α, and IFN-γ. In other words, the picture supports that Astragalus has a real effect of immune regulation and anti-inflammation. However, proportions must be kept: many of the included studies were conducted in China, some were small, and the quality of some evidence is limited. This is promising evidence for a direction of effect, not a definitive proof of significant clinical benefit in every condition.

Study 2: Cycloastragenol / TA-65 and Telomere Lengthening, the Harley et al. 2011 Study

This is the study upon which the entire "anti-aging" story rests. In 2011, a randomized, double-blind, placebo-controlled trial (Harley et al.) was published examining TA-65, the supplement based on cycloastragenol, in 117 relatively healthy CMV carriers aged 53 to 87 over about one year.

The widely cited result: At the low dose, TA-65 was associated with an increase in short telomeres compared to a decrease in the placebo group. Sounds impressive, but this is precisely where caution begins. First, the study was funded by the company that manufactures and markets TA-65, a significant conflict of interest. Second, it measured telomere length, a biomarker, and not a real health outcome: no lifespan extension, disease prevention, or slowing of functional aging was measured here. Lengthening telomeres on paper is not equivalent to a longer, healthier life, and in certain contexts, longer telomeres have even been linked to a higher risk of cancer. This is a critical distinction that marketing prefers to blur.

Study 3: Astragalus as an Adjunct in Oncological Treatment, Meta-Analyses in Lung Cancer

Another studied context is combining Astragalus with chemotherapy. Meta-analyses of trials have examined Astragalus-based herbal preparations combined with platinum-based chemotherapy in patients with advanced NSCLC lung cancer, and some reported a possible improvement in treatment response and a reduction in side effects.

But here too, caution is warranted. Reviewers have repeatedly noted that the quality of a large portion of the trials is low, that a large, independent, placebo-controlled trial with objective outcomes is lacking, and that positive results from low-quality studies have limited significance. Astragalus in an oncological context is a legitimate area of interest, but it is by no means a treatment in itself, and a sick person must not replace or delay conventional treatment because of it. Any such combination must be done only with the knowledge and approval of the oncologist.

What About Kidneys, Heart Disease, and Immunosenescence?

Beyond immunity, telomeres, and oncology, Astragalus has been examined in several other contexts. In some Chinese studies, a potential effect on kidney function and protein excretion in urine (proteinuria) in certain kidney diseases was examined, as well as a potential effect on heart muscle and cardiac markers. The results are interesting but are mostly based on studies of variable quality, so definitive conclusions cannot yet be drawn, and they certainly cannot replace established treatment.

A particularly intriguing area is the connection between Astragalus and immunosenescence (aging of the immune system). Several studies on TA-65 reported a decrease in "senescent" CD8+CD28- T cells, which accumulate with age and are considered a marker of an aging immune system. This is an interesting finding that links the immunity story to the aging story, but it too is based on small studies, some with industry ties. The bottom line repeats itself across all areas: Astragalus is a real and interesting bioactive herb, but expectations from it should remain modest and realistic.

Should You Start Taking Astragalus?

This is precisely why we rated Astragalus Yellow. On one hand, it has a measurable and relatively well-founded immune-inflammatory effect; on the other hand, the telomerase and aging story is inflated far beyond what the evidence supports, is very expensive, and comes with real safety issues. Here are the considerations:

• The telomerase hype, the most important point. The claim that TA-65 or cycloastragenol "extend lifespan" or "slow aging" in humans is simply unproven. What exists is telomere lengthening in a biomarker, in industry-funded studies, without a hard health outcome. Telomere lengthening is not proof of longevity, and the relationship between long telomeres and health is complex and may even include an increased risk of cancer in certain contexts. Do not buy this promise.
• Inflated price. Branded telomerase supplements, led by TA-65, are very expensive, sometimes hundreds of shekels per month. Against weak evidence for real benefit, the cost-benefit ratio is particularly problematic.
• Caution in autoimmune conditions. Because Astragalus stimulates and regulates the immune system, people with autoimmune diseases (such as lupus, multiple sclerosis, or rheumatoid arthritis) should be cautious and consult a doctor, for fear of worsening the condition.
• Interaction with immunosuppressant drugs, critical. People taking immunosuppressant drugs, especially organ transplant recipients, should avoid Astragalus unless a doctor has explicitly approved it, because it may counteract the drug's action and endanger the transplant.

Beyond that, a few things should be remembered. Astragalus in its regular herbal form is generally considered safe and well-tolerated by most healthy adults, and reported side effects are mostly mild (minor digestive discomfort). However, pregnant or nursing women, people with kidney disease, and those taking regular medications should get a doctor's approval before taking it. As always: an herb with real biological activity is precisely the herb to be cautious with, not the opposite.

What Should You Take Away from the Research?

1. Separate immunity from "anti-aging". If you are interested in Astragalus for general immune support, there is decent evidence for that. If it is marketed to you as a supplement that lengthens telomeres and slows aging, view it with skepticism; the science there is much weaker.
2. Do not pay a premium for the telomerase promise. Branded telomerase products are several times more expensive than regular Astragalus powder, against similar or lower proven benefit. Do not pay hundreds of shekels a month for a marketing story.
3. If you have an autoimmune disease, consult first. Astragalus affects the immune system, so it is not automatically safe for someone whose immune system is already attacking their body.
4. If you are taking immunosuppressant drugs or are an organ transplant recipient, avoid it. This is one of the most important warnings here; Astragalus may counteract these drugs. Do not take it without explicit approval from your treating physician.
5. Do not replace medical treatment. Whether it is kidney disease, heart disease, or cancer, Astragalus is at most a possible adjunct supplement with the doctor's knowledge, never a replacement for treatment.

For those who still want to try Astragalus for immune support from a reliable source, you can purchase Astragalus on iHerb and choose a standard root extract from a reliable brand, not necessarily the expensive telomerase products. To check which supplements are truly suitable for your health goals, including immune support, according to your age and condition, you can use our personal supplement checker that rates each supplement based on the quality of evidence.

The Broader Perspective

Astragalus is an excellent case study of the gap between evidence and marketing. On one hand, it is an herb with real biological activity, and relatively decent evidence for immune and anti-inflammatory effects in humans. On the other hand, the "anti-aging" layer built upon it, the telomerase story of cycloastragenol and TA-65, is inflated far beyond what the science truly supports. When you add a particularly high price and safety issues in certain populations, you get a classic yellow profile: an interesting and useful herb in the right context, but not a magic bullet against time.

The practical lesson is twofold. First, be especially wary of any supplement that promises to "lengthen telomeres" or "stop the aging clock," especially when the price is high and the research is funded by the seller. An improved biomarker is not the same as a longer, healthier life. Second, it is important to remember that even an herb with a real effect has only a modest place in the big picture. Healthy immunity and longevity are built primarily from sleep, nutrition, physical activity, stress management, and evidence-based vaccines, and Astragalus can be, at best, a small and cautious addition to them. And that is precisely the perspective we hold here: to rate each supplement according to what the science truly shows, when it is promising, and when it is better to remain cautious, even when the marketing promises us eternity.

References:
Zhang Y. et al., The Effect of Astragalus on Humoral and Cellular Immune Response: A Systematic Review and Meta-Analysis of Human Studies, Complementary Medicine Research, 2023;30(6):535-545 (DOI: 10.1159/000534570)
Harley C.B. et al., A Natural Product Telomerase Activator (TA-65) Lengthens Telomeres in Humans: A Randomized, Double Blind, and Placebo Controlled Study, Rejuvenation Research, 2011;14(1):45-56
Astragalus-containing Chinese herbal combinations for advanced non-small-cell lung cancer: a meta-analysis of 65 clinical trials enrolling 4751 patients, Lung Cancer: Targets and Therapy, 2016